I'm going to guess the hardware switches and key combos went away because they are too confusing for users. I remember constant complaints of "Internet doesn't work" because the wifi hardware switch was turned off. And as the saying goes, if the majority of users are using it wrong, it was designed wrong.

I think Apple picked the right middle ground by making access to the mic and camera a permissions request as well as showing a clear indicator to the user whenever these are active. Steve jobs said the best UI is to ask the user for their data when you want it and keep making them aware of this access every time you use it.